> he's just taking notes

That's how a barrister does part of their work.

When I develop software I'm 'just writing a program'. But I'm not - I'm forming a mental model of what I want to do and working out how to express it.

You can make any job sound silly by reducing it to its constitutive actions.

My point is the barrister does most of their work outside of the software - taking notes is not unique to being a barrister. A software engineer, or artist, or architect, or CAD modeller, or audio engineer, or accountant (just some examples of the kind of work I'm thinking of) do the majority of their work in software. Some of these workflows are doable on an iPad, some of them are not. All of them are doable to a professional level on a regular PC or Mac though.

Actually, handwritten note taking in particular is a professional task that you can not do on a regular PC or Mac. As a theoretical physicist, doing math "on paper" is not something I can do on a PC or Mac, and doing it on an iPad is orders of magnitude better than using actual paper, as it allows for moving things around and revising.